It is understood that mechanical failure is being investigated as a possible cause for Sunday's crash, with investigators to probe if the men may have been alerted to a problem by warning lights in the cockpit shortly after taking off. Mr Doherty was highly experienced and was well on his way to fulfilling his lifelong dream of becoming a commercial pilot.

Mr Deegan was also a keen and experienced flyer, understood to be planning to get a commercial licence.

He worked as a team leader at Tesco in Birr where shocked co-workers spoke of him as having "a heart of gold".

The men's Cessna 150H aircraft landed upside down in an overgrown field, and two separate investigations are now under way by gardai and the Air Accident Investigation Unit (AAIU).

It is understood the plane took off from Birr Airfield and was headed south when it began to experience difficulties. Air traffic control at Shannon raised the alarm when it disappeared from radar screens shortly before 5pm on Sunday.

The men's bodies were removed from the scene late on Sunday night, and the mangled wreckage was taken away yesterday afternoon.

AAIU head Jurgen Whyte said: "We're relying on witness and a detailed examination. It's quite an elderly aircraft but that's not unusual.